What is the difference between 6AT, 8AT and 9AT inside an automatic transmission? Is the more gears the more fuel efficient?

Hello everyone, I'm happy to talk about cars with you.

Nowadays the traditional automatic transmission has been hit more and more from cvt continuously variable transmission and dual clutch transmission! Especially the 6-speed low-end automatic transmission, but also a lot of 6-speed or 7-speed dual-clutch gearbox, cvt continuously variable transmission replaced! Compared to the 6-speed at automatic transmission, dual clutch transmission and cvt can realize a wider range of transmission ratios, and further improve transmission efficiency! And in response to competitive pressure from cvt CVTs and dual clutch automatics, the traditional AT automatic transmission began to evolve towards more gears! Like the automatic transmission used in the 2.5 liter Toyota Camry. The Honda Corolla 2.0t turbocharged engine version, on the other hand, uses a 9AT automatic transmission. Luxury brands like BMW and Mercedes-Benz also use 9-speed or 8-speed AT automatic transmissions.

The biggest difference between the 6at and the 8at or 9at is the number of gears! And with the additional gears, these higher grade automatic transmissions will get a wider range of ratios! And the denser ratios will make the transmission shift smoother. More gears will also allow the engine to run at a more suitable RPM range! A better balance of power and fuel economy! A wider range of ratios can make the car more powerful at low speeds and more fuel efficient at high speeds!

Let's say, the same three-meter floor height, if the staircase is made into a 6-steps, we walk from the first floor to the second floor will be very hard, the step to take a bigger step! Will also consume more physical strength! And if we make the stairs 8 or 9, we will be much easier to go from the 1st floor to the 2nd floor! It's more energy efficient, the steps are smaller, and we'll get from the 1st floor to the 2nd floor more smoothly! However, while more gears bring better acceleration smoothness, there may be some negative effects on the acceleration time of 100 kilometers! And the biggest negative impact is the sharp increase in the cost of the gearbox. So at present more mainstream models, even with at automatic transmission will use lower cost, but at the same time more practical 6at automatic transmission, and those high-end models will only use 8AT or 9at automatic transmission.

Finally, to answer the question, an 8at or 9at automatic transmission has more gears and wider ratios than a more traditional 6at automatic transmission! Theoretically, with the same engine, it is also more favorable for the engine to work in a more suitable speed range, and it is also easier to achieve a balance between power and fuel economy! Naturally, it will perform better in terms of fuel economy! There is no doubt about it! Well, today's brief introduction is here, if you have a different view, you are welcome to leave me a message, thank you.

The difference is that the more gears you have, the more fuel-efficient you are in theory, because more gears means you can keep the speed at a lower rpm, and a lower rpm saves you fuel, but of course this is not absolute, and some of these sport-tuned gearboxes will intentionally delay the shift timing, so that the car stays at a high rpm as much as possible to get better power, so this kind of gearboxes won't be fuel-efficient for sure. There are also more and more gears in today's transmissions, even some more than, say, the Freelander's nine-speed transmission, which basically doesn't hang up in ninth gear at the legal speed limit, so what's the point of its multiple gears? Of course you can't judge a transmission by just how many gears it has, the first thing about a good transmission is that it's reliable and durable, then it's smooth, and if then it's fuel-efficient, and of course if you're a regular violent driver you need to consider whether it's tuned to be sporty or not? Shifting too early saves fuel but also loses power, and there are also some gearboxes with more delayed shifts, which can also have a greater impact on sportiness.

Theoretically, the more gears, the denser the ratio, the less power loss, the more fuel-efficient, the smoother the smoothness will be better, the speed will be faster, but this is all to match the engine, in general, the market is the more gears, the better, you can test-drive the specifics of the car to know

The more gears, the more the frustration is lighter, the better the feeling of comfort. The fuel savings are minimal.